Bariatric surgery procedures, such a sleeve gastrectomy, the Rouen-Y gastric bypass (RYGB) and the bileo-pancreatic diversion (BPD), modify food intake and/or absorption within the gastrointestinal system to effect weight loss in obese patients. These procedures affect metabolic processes within the gastrointestinal system, by either short circuiting certain natural pathways or creating different interaction between the consumed food, the digestive tract, its secretions and the neuro-hormonal system regulating food intake and metabolism. In the last few years there has been a growing clinical consensus that obese patients who undergo bariatric surgery see a remarkable resolution of their type-2 Diabetes Mellitus (T2DM) soon after the procedure. The remarkable resolution of diabetes after RYGB and BPD typically occurs too fast to be accounted for by weight loss alone, suggesting there may be a direct impact on glucose homeostasis. The mechanism of this resolution of T2DM is not well understood, and it is quite likely that multiple mechanisms are involved.
One of the drawbacks of bariatric surgical procedures is that they require fairly invasive surgery with potentially serious complications and long patient recovery periods. In recent years, there is an increasing amount of ongoing effort to develop minimally invasive procedures to mimic the effects of bariatric surgery using minimally invasive procedures. One such procedure involves the use of gastrointestinal implants that modify transport and absorption of food and organ secretions. For example, U.S. Pat. No. 7,476,256 describes an implant having a tubular sleeve with anchoring barbs, which offer the physician limited flexibility and are not readily removable or replaceable. Moreover, stents with active fixation means, such as barbs that deeply penetrate into surrounding tissue, may potentially cause tissue necrosis and erosion of the implants through the tissue, which can lead to complications, such as bacterial infection of the mucosal tissue or systemic infection. Also, due to the intermittent peristaltic motion within the digestive tract, implants such as stents have a tendency to migrate.
Gastroparesis is a chronic, symptomatic disorder of the stomach that is characterized by delayed gastric emptying in the absence of mechanical obstruction. The cause of gastroparesis is unknown, but it may be caused by a disruption of nerve signals to the intestine. The three most common etiologies are diabetes mellitus, idiopathic, and postsurgical. Other causes include medication, Parkinson's disease, collagen vascular disorders, thyroid dysfunction, liver disease, chronic renal insufficiency, and intestinal pseudo-obstruction. The prevalence of diabetic gastroparesis (DGP) appears to be higher in women than in men, for unknown reasons.
Diabetic gastroparesis affects about 40% of patients with type-1 diabetes and up to 30% of patients with type-2 diabetes and especially impacts those with long-standing disease. Both symptomatic and asymptomatic DGP seem to be associated with poor glycemic control by causing a mismatch between the action of insulin (or an oral hypo-glycemic drug) and the absorption of nutrients. Treatment of gastroparesis depends on the severity of the symptoms.
Several inventors have recently described intra-luminal implants and implant delivery tools to mimic the effect of bariatric surgery procedures such as gastric and intestinal bypass for the treatment of obesity. In particular to mimic the effects of a popular surgical procedure called the Rouen-Y Gastric bypass in which most of the stomach is excised and a lower part of the small intestine is anastamosed to a small stomach pouch, several inventors have proposed implants that anchor at the gastroesophageal junction and reroute food to the small intestine. In many instances these implants then also anchor sleeves or stented sleeves that act as bypass conduits for mimicking stomach and intestinal bypass surgeries.
These systems, however, have significant shortcomings in terms of clinical side effects and complications. Implants that bypass the stomach with artificial sleeve like structures or conduits do not have motility like in a surgical gastric bypass where the anastomosed section of the intestine actively propels food from the esophagus (e.g., the system described in U.S. Pat. No. 7,837,669). Hence in early clinical results using this approach patients have complained about dysphagia (difficulty swallowing) as the solid undigested food is not easily pushed forward in to the small intestine from the esophagus through these artificial passageways. Also, the delivery system contemplated to be used to perform this procedure is complicated (e.g., U.S. Patent Publication 2008/0167606). It involves placing a sleeve element into the small intestine, where the sleeve element is first delivered in a sock-like configuration and then is extended into the small intestine by unrolling it. Accurate placement with this system is difficult.